The present invention relates to a receiver, such as for a hearing aid, and more particularly, to a receiver having an armature welded to the magnet stack at the peripheral edge of the armature.
Moving armature transducers, or receivers, such as those used in miniature hearing aids, are sensitive to the crystalline condition of metal parts in the receiver""s magnetic circuit. Components in the magnetic circuit should have high permeability, even in the presence of high magnetic fields, if the transducer is to have good distortion performance and high sensitivity. Careful annealing of the metal parts will produce good performance.
One particularly sensitive point is where the armature connects to the metal housing for the magnets, or stack. The armature is normally resistance welded to the stack. This process inevitably damages the magnetic properties of the armature and the stack in the weld area. As these transducers are quite small, the damaged area is a significant portion of the available interface area between the armature and the stack.
Resistive welding is a simple and economical way to attach the armature to the stack. Unfortunately, it is very difficult to limit or control the weld area, as a weld will form anywhere there is good mechanical contact and the current density is high enough.
The present invention is provided to solve these and other problems.
It is an object of the invention to provide a receiver for converting electrical energy to acoustical energy.
In accordance with the invention, the receiver comprises an armature having a peripheral edge, a magnet stack, and means for attaching the armature to the magnet stack. The attaching means comprises a weld joint at the peripheral edge of the armature.
It is contemplated that the weld joint is a laser weld joint.
It is further contemplated that the weld joint comprises a plurality of spot weld joints disposed on opposing portions of the peripheral edge.
It is still further contemplated that the attaching means includes an adhesive, such as an epoxy disposed between the armature and the stack.
It is a further object of the invention to provide a method of manufacturing a receiver for converting electrical energy to acoustical energy.
In accordance with this aspect of the invention, the method comprises the steps of providing an armature having a peripheral edge, providing a magnet stack adjacent the armature, and welding the armature to the magnet stack at the peripheral edge of the armature.
It is contemplated that the weld joint is a laser weld joint.
It is further contemplated that the weld joint comprises a plurality of spot weld joints disposed on opposing portions of the peripheral edge.
It is still further contemplated that the method includes the step of providing an adhesive, such as an epoxy, disposed between the armature and the stack.
Other advantages and aspects of the present invention will become apparent upon reading the following description of the drawings and detailed description of the invention.